Display apparatus

Abstract

A display apparatus is provided to include a pixel array composed of a plurality of pixels. Each pixel includes a pulse-generating unit producing a first pulse and a second pulse with opposite phases; a first switching unit; a light-emitting unit; and a second switching unit. The first switching unit, the light-emitting unit, and the second switching unit are connected in series, the first switching unit is controlled by the first pulse, and the second switching unit is controlled by the second pulse, and the first switching unit and the second switching unit are configured to be turned on or turned off synchronously.

What is claimed is: 
     
       1. A display apparatus comprising:
 a pixel array composed of a plurality of pixels, wherein each pixel comprises:
 a pulse-generating unit producing a first pulse and a second pulse with opposite phases; 
 a first switching unit; 
 a light-emitting unit; and 
 a second switching unit, 
 wherein the first switching unit, the light-emitting unit, and the second switching unit are connected in series, the first switching unit is controlled by the first pulse, and the second switching unit is controlled by the second pulse, and the first switching unit and the second switching unit are configured to be turned on or turned off synchronously. 
 
 
     
     
       2. The display apparatus according to  claim 1 , wherein the pulse-generating unit comprises:
 a voltage comparator having a first input terminal and a second input terminal, wherein the first input terminal is input with a data voltage and the second input terminal is input with a sawtooth pulse, and an output terminal of the voltage comparator outputs the first pulse; and 
 an inverter, wherein an input terminal of the inverter is connected to an output terminal of the voltage comparator and an output terminal of the inverter is configured to output the second pulse. 
 
     
     
       3. The display apparatus according to  claim 1 , wherein the first switching unit comprises a NMOS transistor; and the second switching unit comprises a PMOS transistor. 
     
     
       4. The display apparatus according to  claim 2 , wherein the pulse-generating unit further comprises a buffer unit, and an output pulse of the voltage comparator controls the first switching unit through the buffer unit. 
     
     
       5. The display apparatus according to  claim 4 , wherein the buffer unit comprises a time-delay circuit or a voltage follower. 
     
     
       6. The display apparatus according to  claim 4 , wherein the voltage comparator comprises a two-stage open-loop comparator;
 the inverter comprises an inverted output buffer; and 
 the buffer unit comprises a forward output buffer. 
 
     
     
       7. The display apparatus according to  claim 1 , wherein, the light-emitting unit comprises a plurality of light-emitting elements with same color, and the light-emitting elements are connected in series. 
     
     
       8. The display apparatus according to  claim 7 , wherein the plurality of light-emitting elements comprises a first LED die and a second LED die which are selected from a group of LED dies in a manner that a brightness of the first LED die is lower than a median value of brightness of the group of LED dies, and a brightness of the second LED die is higher than the median value of the brightness of the group of LED dies, wherein the brightness of the LED die is dies are measured under the same current. 
     
     
       9. The display apparatus according to  claim 7 , wherein the color emitted by the light-emitting unit includes one of red, green, blue, orange, cyan, yellow and white. 
     
     
       10. The display apparatus according to  claim 1 , wherein the light-emitting unit comprises a plurality of light-emitting elements connected in parallel and light-emitting elements emit the same color. 
     
     
       11. The display apparatus according to  claim 10 , wherein the plurality of light-emitting elements comprises a first LED die and a second LED die which are selected from a group of LED dies in a manner that a brightness of the first LED die is lower than a median value of brightness of the group of LED dies, and a brightness of the second LED die is higher than the median value of the brightness of the group of LED dies, wherein the brightness of the LED dies are measured under the same voltage. 
     
     
       12. The display apparatus according to  claim 10 , wherein, the color emitted by the light-emitting unit includes one of red, green, blue, orange, cyan, yellow and white. 
     
     
       13. The display apparatus according to  claim 1 , wherein the light-emitting unit comprises at least one organic light-emitting diode or/and at least one inorganic light-emitting diode. 
     
     
       14. The display apparatus according to  claim 2 , wherein the pixel array comprises
 a first group of pixels and a second group of pixels; 
 a sawtooth pulse-generating unit configured to output a first sawtooth pulse to the first group of pixels and output a second sawtooth pulse to the second group of pixels, wherein the first sawtooth pulse and the second sawtooth pulse have opposite phases; 
 the voltage comparators in the first group of pixels are configured to receive the first sawtooth pulse as an input, the voltage comparators in the second group of pixels are configured to receive the second sawtooth pulse as an input. 
 
     
     
       15. The display apparatus according to  claim 14 , wherein the pixel array comprises a plurality of odd number rows comprising the first group of pixels, and a plurality of even number rows comprising the second group of pixels, the odd number row and the even number row are alternately arranged. 
     
     
       16. The display apparatus according to  claim 15 , wherein the sawtooth pulse-generating unit includes a voltage buffer and an inverter, wherein the voltage buffer is configured to output the first sawtooth pulse to control the pixels in the odd number rows, and the inverter of the sawtooth pulse-generating unit is configured to output the second sawtooth pulse to control the pixels in the even number rows. 
     
     
       17. The display apparatus according to  claim 1 , wherein the pulse-generating unit comprises a plurality of transistors including two NMOS transistors and two PMOS transistors, wherein one of the two NMOS transistor and one of the two PMOS transistors form an output buffer unit to output the first pulse, and wherein another one of the two PMOS transistors and another one of the two NMOS transistors form another output buffer unit to output the second pulse. 
     
     
       18. The display apparatus according to  claim 7 , wherein, driven by the same current, a brightness difference between different light-emitting units but having the same color is less than 10% of an average brightness of the light-emitting units having the same color. 
     
     
       19. The display apparatus according to  claim 10 , wherein, driven by the same voltage, a brightness difference between different light-emitting units but having the same color is less than 10% of an average brightness of the light-emitting units having the same color.